Trans-sarcolemmal Ca2+ movements associated with contraction of the rabbit right ventricular wall

Journal Article · Tue Dec 01 04:00:00 EST 1987 · Circ. Res.; (United States)

DOI:https://doi.org/10.1161/01.RES.61.6.805· OSTI ID:5721058

Pierce, G N; Rich, T L; Langer, G A

The purpose of this study was to examine the movements of Ca2+ into the myocardium from the extracellular space during the course of muscle contraction. Equilibration of the rabbit right ventricular wall with perfusate containing /sup 45/Ca was measured by collecting effluent droplets over time. This protocol was carried out in a quiescent muscle and then repeated 15-20 minutes later in an identical fashion except that halfway through the collection period the muscle was stimulated to contract. We were thus able to quantitate the contraction-dependent changes in /sup 45/Ca movements. In control experiments using (/sup 58/Co)EDTA as an extracellular space marker, we observed that contraction altered the volume of this space. This alteration in extracellular space was relatively small, and the quantitation of /sup 45/Ca movements was corrected for this change. The addition of 1 microM Bay K 8644 to the perfusate stimulated tension and augmented Ca2+ depletion from the extracellular space. The addition of 15 microM nifedipine to the perfusate significantly reduced both tension development and Ca2+ depletion from the extracellular space of the muscle. Net contraction-dependent movement of Ca2+ from the extracellular space into the myocardium under control conditions at 1 mM (Ca2+) was 10-14 mumol Ca2+/kg tissue wet wt/beat. This value indicates either a large contribution of Ca2+-induced Ca2+ release from the sarcoplasmic reticulum and/or significant contribution of sarcolemmal bound Ca2+ to excitation-contraction coupling in the rabbit ventricle.

• Research Organization: Univ. of California, Los Angeles
• OSTI ID: 5721058
• Journal Information: Circ. Res.; (United States), Journal Name: Circ. Res.; (United States) Vol. 61:6; ISSN CIRUA
• Country of Publication: United States
• Language: English

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551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CALCIUM 45
CALCIUM COMPOUNDS
CALCIUM ISOTOPES
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CHELATING AGENTS
COBALT 58
COBALT ISOTOPES
CONTRACTION
DAYS LIVING RADIOISOTOPES
EDTA
ELECTRON CAPTURE RADIOISOTOPES
EVEN-ODD NUCLEI
EXTRACELLULAR SPACE
HEART
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANE TRANSPORT
MUSCLES
MYOCARDIUM
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PERFUSED ORGANS
RABBITS
RADIOISOTOPES
SPACE
TRACER TECHNIQUES
VERTEBRATES